1. Field of the Invention.
The invention relates to a device for the signature-based protection of electronic transactions which are executed in particular by banking applications on personal mobile terminals or other money or payment systems (e.g. POS—point of sale) and require the integrity of the digitally signed information and the identification of the originator of this information to be beyond doubt.
2. Description of the Related Art.
Electronic signatures are always used when there is a requirement to identify the originator or sender of an electronic document or data record beyond doubt and to guarantee the integrity of the signed electronic information. One example of a security-critical area which is becoming increasing important in everyday life is banking applications such as home banking or mobile banking. It is immediately apparent what might happen if a malicious third party could pretend to be the owner of a bank account that does not belong to him.
With the use of mobile systems in both private and commercial areas and in the fields of health or public administration, the risks resulting therefrom multiply if the integrity of the information transmitted cannot be guaranteed or if the identity of the originator cannot be established beyond doubt.
Depending upon the required level of security and the preferred security procedure, smart cards are used in combination with a smart card reader.
The relevant procedures, with reference to which the prior art will be described in the following, originate from the fields of security in payment transactions, online-banking security and chip technology. The sheer number of security procedures on the Internet, which have been developed in the last ten years, shows how important it is to guarantee the security and reliability of communication on the Internet. Procedures which are based on the use of TAN lists to safeguard a transaction are now no longer considered to be secure and have been superseded by other procedures.
The chip card is now at the centre of all security procedures to be taken seriously. It is considered to be a technically secure carrier of secret encoded information, it is always held by the customer (owned component) and also now represents a valuable and secure medium for all users of which they take particular care and the loss of which they report immediately to the issuer (for example, the bank). For example, a credit institution can always be confident that the chip card is with its customer and that this is actually the person carrying out the transactions because the loss of the chip card would be reported immediately. A synonym for the term chip card is smart card. The latter is also used in this document in particular when this relates to the crypto microcontroller of a chip card, the actual building block for cryptographic operations.
The majority of smart card based security procedures require a smart card reader. Due to current standards and in cases where a high level of security is to be achieved, card readers of this kind nowadays have a display and a separate keyboard unit.
Smart card readers are devices which control chip cards. In this case, data are not only read, they are also written or applications are controlled on the chip card; for this reason, they are also referred to as smart card terminals [1]. There are four security classes for smart card readers specified at the DK (German banking industry). Security classes 1 and 2 are of no interest for a serious security level. Smart card readers of security class 3 have a display and a keyboard and additional functions which enable payment with the money card on the internet. In addition to the features of class 3, smart card readers of security class 4 also have their own tamper-proof identity. This is enabled by means of an additional chip card. If a smart card reader is connected to a PC via USB or a serial interface, it is recognised by proprietary or standardised software interfaces and can communicate with an application. The present standard for interfaces of this kind is PC/SC [3], for which there are both Windows and Linux implementations. The Secoder specification [2] goes beyond the features of security class 3. A smart card reader built according to this specification includes a firewall, which protects against possible manipulation while the device interacts with the user via the display and keyboard (for example PIN entry) or processes data for the signature process with a chip card. In addition, standards, such as the Secoder standard require increasingly more information to be visible to users on the screen of the smart card reader before they release the transaction via the keyboards.
Despite rapid and exemplary developments in the field of mobile terminals (smartphones, tablets, etc.), adaptation of smart card readers could not keep pace appropriately. For example, in practice, present-day devices, which are also used in combination with mobile terminals, have more or less serious disadvantages with respect to handling or operation thus rendering them unsuitable for widespread use. The smart card reader is a mandatory further device for users that they must always have with them when there is a requirement for security-critical communications (for example mobile banking). To enable present-day smart card readers to fulfil all requirements of security standards and mobile communication, they either have large dimensions or are compact and space-saving, but then they only have tiny keys and displays.